1. Field of the Invention
The present invention relates to a hose coupling with a clamp which can be clamped around a longitudinal axis, wherein the edges of the clamp are located closer to the longitudinal axis than an area of the clamp located between the edges. The hose coupling further includes a pipe, wherein an end portion of the hose can be pushed onto an end portion of the pipe and can be clamped by means of the clamp. The end portion of the pipe is provided with a circumferential holding rib, wherein the end portion of the hose can be pushed past the holding rib and wherein the clamp can be clamped on the hose above the holding rib so that the hose is secured between the holding rib and the clamp.
2. Description of the Related Art
In a known hose coupling of this type disclosed in DE 29 19 939 A1, the clamp body has the shape of a C-ring of plastics material with clamping jaws integrally formed at the ends of the C-ring, wherein a clamping screw is inserted between the clamping jaws. The contour of the axial cross-section of the clamp body is preferably tripezoidally shaped in the interior of the clamp body, but is approximately rectangular on the outside. Alternatively, the clamp body may also have an axial cross-section which is, for example, circular segment-shaped or elliptical in the interior. The pipe may be, for example, a pipe piece which is also of plastics material. The contour of the axial cross-section of the holding rib is shaped so as to correspond to the inner contour of the clamp body, i.e., the contour is also preferably trapezoidally shaped or, for example, circular or elliptical. The plastics material is preferably reinforced with glass fibers. Consequently, its thermal expansion coefficient is low, but its elasticity is also low. Therefore, the clamp body is just sufficiently flexible in order to clamp the clamp. However, because of its high geometrical moment of inertia, this requires a correspondingly high clamping force. Consequently, the clamp body is not capable of elastically following the yielding or “flowing away” of the hose material due to the radial clamping pressure of the clamp, in order to ensure permanent tightness of the connection between the hose and the pipe. The tightness of the connection is essentially based on the fact that the elastic hose material is held under pretension in the space between the clamp and the holding rib. When the elasticity of the hose material decreases due to the clamping pressure and thermal aging, the connection can still become untight when the fluid pressure in the hose and pipe is high.
EP 0 166 756 B1 discloses arranging a resilient, uniformly thick metal band between a worm drive hose clamp and a hose to be clamped on a smooth or unribbed metal pipe, wherein the axial cross-sectional contour is uniformly outwardly arched in an axially middle portion and is provided at the edges of the middle portion with radially inwardly arched beads. During tensioning of the worm drive hose clamp, the metal band is pressed with its middle portion and the beads against the hose. This causes the hose material in the area between the beads to be pressed axially and radially, in order to achieve as high a sealing effect as possible by means of the elastic hose material in the middle portion of the metal band between the beads. Simultaneously, the metal band is supposed to facilitate an automatic after sealing when the elasticity of the hose material decreases, because the beads press against the hose with radial spring pretension and are supposed to elastically move in when the hose material yields. Aside from the fact that the worm drive hose clamp, which effects clamping of the metal band, is complicated, it impedes the free elastic mobility of the metal band. Moreover, because of their high geometrical moment of inertia, the beads contribute to the stiffening of the metal band.